System and method for controlling actuators of an engine to adjust intake airflow when the engine is starting

ABSTRACT

A system according to the principles of the present disclosure includes a target area module and a throttle actuator module. The target area module determines a target opening area of a throttle valve of an engine based on a first target pressure within an intake manifold of the engine when the engine is starting. The throttle actuator module actuates the throttle valve based on the target opening area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/172,993, filed on Jun. 9, 2015. The disclosure of the above application is incorporated herein by reference in its entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. 14/798,876 filed on Jul. 14, 2015. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to internal combustion engines, and more particularly, to systems and methods for controlling actuators of an engine to adjust intake airflow when the engine is starting.

BACKGROUND

The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. Air flow into the engine is regulated via a throttle. More specifically, the throttle adjusts throttle area, which increases or decreases air flow into the engine. As the throttle area increases, the air flow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders and/or to achieve a desired torque output. Increasing the amount of air and fuel provided to the cylinders increases the torque output of the engine.

In spark-ignition engines, spark initiates combustion of an air/fuel mixture provided to the cylinders. In compression-ignition engines, compression in the cylinders combusts the air/fuel mixture provided to the cylinders. Spark timing and air flow may be the primary mechanisms for adjusting the torque output of spark-ignition engines, while fuel flow may be the primary mechanism for adjusting the torque output of compression-ignition engines.

Engine control systems have been developed to control engine output torque to achieve a desired torque. Traditional engine control systems, however, do not control the engine output torque as accurately as desired. Further, traditional engine control systems do not provide a rapid response to control signals or coordinate engine torque control among various devices that affect the engine output torque.

SUMMARY

A system according to the principles of the present disclosure includes a target area module and a throttle actuator module. The target area module determines a target opening area of a throttle valve of an engine based on a first target pressure within an intake manifold of the engine when the engine is starting. The throttle actuator module actuates the throttle valve based on the target opening area.

Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example engine system according to the present disclosure;

FIG. 2 is a functional block diagram of an example engine control system according to the present disclosure;

FIG. 3 is a functional block diagram of an example air control module according to the present disclosure;

FIG. 4 is a functional block diagram of an example area module according to the present disclosure;

FIG. 5 is a flowchart depicting an example method of controlling a throttle valve, intake and exhaust valve phasing, a wastegate, and an exhaust gas recirculation (EGR) valve using model predictive control according to the present disclosure;

FIG. 6 is a flowchart depicting an example method of controlling actuators to adjust intake airflow during an engine start according to the present disclosure; and

FIG. 7 is a graph illustrating example control signals and example sensor signals during an engine start according to the present disclosure.

In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

An engine control module (ECM) controls torque output of an engine. More specifically, the ECM controls actuators of the engine based on target values, respectively, based on a requested amount of torque. For example, the ECM controls intake and exhaust camshaft phasing based on target intake and exhaust phaser angles, a throttle valve based on a target throttle opening, an exhaust gas recirculation (EGR) valve based on a target EGR opening, and a wastegate of a turbocharger based on a target wastegate opening or position.

The ECM could determine the target values individually using multiple single input single output (SISO) controllers, such as proportional integral derivative (PID) controllers. However, when multiple SISO controllers are used, the target values may be set to maintain system stability at the expense of possible fuel consumption decreases. Additionally, calibration and design of the individual SISO controllers may be costly and time consuming.

The ECM of the present disclosure generates target values using a model predictive control (MPC) module. The MPC module identifies sets of possible target values based on, for example, a torque request, and selects one of the sets of possible target values having a lowest cost. The MPC module sets the target values to the respective possible target values of the selected one of the sets.

According to the present disclosure, the target values generated by the MPC module include a target pressure ratio across the throttle valve. More specifically, the MPC module determines sets of possible target values including possible intake and exhaust phaser angles, possible target pressure ratios across the throttle valve, possible target EGR valve openings, and possible target wastegate openings. The MPC module selects one of these sets of possible target values and, in certain conditions, sets the target pressure ratio across the throttle valve to the possible target pressure ratio of the selected one of the sets. The ECM then converts the target pressure ratio into a target throttle opening. The MPC module also sets the target intake phaser angle, the target exhaust phaser angle, the target wastegate opening, and the target EGR valve opening to the possible target intake phaser angle, the possible target exhaust phaser angle, the possible target wastegate opening, and the possible target EGR valve opening, respectively, of the selected one of the sets.

As noted above, the MPC module may identify the set of possible values based on a torque request. However, during an engine start, controlling an engine based on a torque request may not be desirable, as combustion is not yet established or stable and the torque output by the engine is difficult to determine. Thus, when starting an engine, some ECMs control actuators of the engine based on calibrated values in an open-loop manner. For example, during an engine start, some ECMs may control a throttle valve based on calibrated values of a throttle position. The ECMs may then transition to controlling the engine based on a desired torque after the engine is started. Developing the calibrated values requires time and effort, and transitioning from open-loop control to torque-based control may yield abrupt changes in the speed of the engine.

An ECM according to the present disclosure reduces calibration time by controlling actuators of an engine based on a target pressure in an intake manifold of the engine when the engine is starting. In one example, the ECM determines a first target pressure ratio across a throttle valve of the engine based on the target intake manifold pressure, and controls the throttle valve based on the target pressure ratio when the engine is starting. The ECM also determines a second pressure ratio across the throttle valve using MPC. Then, during a transition period after the engine is started, the ECM controls the airflow actuators based on whichever one of the first pressure ratio and the second pressure ratio has a greater value. Thus, if a driver tips into an accelerator pedal during the transition period, the ECM responds to the acceleration request.

When the transition period ends, the ECM may initialize the torque request used to identify the set of possible values to avoid abrupt changes in the engine speed. In one example, the ECM predicts the torque output of the engine based on the first target pressure ratio using MPC, and sets the torque request equal to the predicted torque output of the engine. The ECM may then adjust the initialized torque request at a predetermined rate to gradually decrease a difference between an uninitialized value of the torque request and the initialized torque request.

Referring now to FIG. 1, a functional block diagram of an example engine system 100 is, presented. The engine system 100 includes an engine 102 that combusts an air/fuel mixture to produce drive torque for a vehicle based on driver input from a driver input module 104. The engine 102 may be a gasoline spark ignition internal combustion engine.

Air is drawn into an intake manifold 110 through a throttle valve 112. For example only, the throttle valve 112 may include a butterfly valve having a rotatable blade. An engine control module (ECM) 114 controls a throttle actuator module 116, which regulates opening of the throttle valve 112 to control the amount of air drawn into the intake manifold 110.

Air from the intake manifold 110 is drawn into cylinders of the engine 102. While the engine 102 may include multiple cylinders, for illustration purposes a single representative cylinder 118 is shown. For example only, the engine 102 may include 2, 3, 4, 5, 6, 8, 10, and/or 12 cylinders. The ECM 114 may instruct a cylinder actuator module 120 to selectively deactivate some of the cylinders, which may improve fuel economy under certain engine operating conditions.

The engine 102 may operate using a four-stroke cycle. The four strokes, described below, may be referred to as the intake stroke, the compression stroke, the combustion stroke, and the exhaust stroke. During each revolution of a crankshaft (not shown), two of the four strokes occur within the cylinder 118. Therefore, two crankshaft revolutions are necessary for the cylinder 118 to experience all four of the strokes.

During the intake stroke, air from the intake manifold 110 is drawn into the cylinder 118 through an intake valve 122. The ECM 114 controls a fuel actuator module 124, which regulates fuel injection to achieve a target air/fuel ratio. Fuel may be injected into the intake manifold 110 at a central location or at multiple locations, such as near the intake valve 122 of each of the cylinders. In various implementations (not shown), fuel may be injected directly into the cylinders or into mixing chambers associated with the cylinders. The fuel actuator module 124 may halt injection of fuel to cylinders that are deactivated.

The injected fuel mixes with air and creates an air/fuel mixture in the cylinder 118. During the compression stroke, a piston (not shown) within the cylinder 118 compresses the air/fuel mixture. A spark actuator module 126 energizes a spark plug 128 in the cylinder 118 based on a signal from the ECM 114, which ignites the air/fuel mixture. The timing of the spark may be specified relative to the time when the piston is at its topmost position, referred to as top dead center (TDC).

The spark actuator module 126 may be controlled by a timing signal specifying how far before or after TDC to generate the spark. Because piston position is directly related to crankshaft rotation, operation of the spark actuator module 126 may be synchronized with crankshaft angle. Generating spark may be referred to as a firing event. The spark actuator module 126 may have the ability to vary the timing of the spark for each firing event. The spark actuator module 126 may vary the spark timing for a next firing event when the spark timing is changed between a last firing event and the next firing event. The spark actuator module 126 may halt provision of spark to deactivated cylinders.

During the combustion stroke, the combustion of the air/fuel mixture drives the piston away from TDC, thereby driving the crankshaft. The combustion stroke may be defined as the time between the piston reaching TDC and the time at which the piston reaches bottom dead center (BDC). During the exhaust stroke, the piston begins moving away from BDC and expels the byproducts of combustion through an exhaust valve 130. The byproducts of combustion are exhausted from the vehicle via an exhaust system 134.

The intake valve 122 may be controlled by an intake camshaft 140, while the exhaust valve 130 may be controlled by an exhaust camshaft 142. In various implementations, multiple intake camshafts (including the intake camshaft 140) may control multiple intake valves (including the intake valve 122) for the cylinder 118 and/or may control the intake valves (including the intake valve 122) of multiple banks of cylinders (including the cylinder 118). Similarly, multiple exhaust camshafts (including the exhaust camshaft 142) may control multiple exhaust valves for the cylinder 118 and/or may control exhaust valves (including the exhaust valve 130) for multiple banks of cylinders (including the cylinder 118). In various other implementations, the intake valve 122 and/or the exhaust valve 130 may be controlled by devices other than camshafts, such as camless valve actuators. The cylinder actuator module 120 may deactivate the cylinder 118 by disabling opening of the intake valve 122 and/or the exhaust valve 130.

The time when the intake valve 122 is opened may be varied with respect to piston TDC by an intake cam phaser 148. The time when the exhaust valve 130 is opened may be varied with respect to piston TDC by an exhaust cam phaser 150. A phaser actuator module 158 may control the intake cam phaser 148 and the exhaust cam phaser 150 based on signals from the ECM 114. When implemented, variable valve lift (not shown) may also be controlled by the phaser actuator module 158.

The engine system 100 may include a turbocharger that includes a hot turbine 160-1 that is powered by hot exhaust gases flowing through the exhaust system 134. The turbocharger also includes a cold air compressor 160-2 that is driven by the turbine 160-1. The compressor 160-2 compresses air leading into the throttle valve 112. In various implementations, a supercharger (not shown), driven by the crankshaft, may compress air from the throttle valve 112 and deliver the compressed air to the intake manifold 110.

A wastegate 162 may allow exhaust to bypass the turbine 160-1, thereby reducing the boost (the amount of intake air compression) provided by the turbocharger. A boost actuator module 164 may control the boost of the turbocharger by controlling opening of the wastegate 162. In various implementations, two or more turbochargers may be implemented and may be controlled by the boost actuator module 164.

An air cooler (not shown) may transfer heat from the compressed air charge to a cooling medium, such as engine coolant or air. An air cooler that cools the compressed air charge using engine coolant may be referred to as an intercooler. An air cooler that cools the compressed air charge using air may be referred to as a charge air cooler. The compressed air charge may receive heat, for example, via compression and/or from components of the exhaust system 134. Although shown separated for purposes of illustration, the turbine 160-1 and the compressor 160-2 may be attached to each other, placing intake air in close proximity to hot exhaust.

The engine system 100 may include an exhaust gas recirculation (EGR) valve 170, which selectively redirects exhaust gas back to the intake manifold 110. The EGR valve 170 may be located upstream of the turbocharger's turbine 160-1. The EGR valve 170 may be controlled by an EGR actuator module 172 based on signals from the ECM 114.

A position of the crankshaft may be measured using a crankshaft position (CKP) sensor 180. A rotational speed of the crankshaft (an engine speed) may be determined based on the crankshaft position. A temperature of the engine coolant may be measured using an engine coolant temperature (ECT) sensor 182. The ECT sensor 182 may be located within the engine 102 or at other locations where the coolant is circulated, such as a radiator (not shown).

A pressure within the intake manifold 110 may be measured using a manifold absolute pressure (MAP) sensor 184. In various implementations, engine vacuum, which is the difference between ambient air pressure and the pressure within the intake manifold 110, may be measured. A mass flow rate of air flowing into the intake manifold 110 may be measured using a mass air flow (MAF) sensor 186. In various implementations, the MAF sensor 186 may be located in a housing that also includes the throttle valve 112.

The throttle actuator module 116 may monitor the position of the throttle valve 112 using one or more throttle position sensors (TPS) 190. A pressure of air input to the throttle valve 112 may be measured using a throttle inlet air pressure (TIAP) sensor 191. An ambient temperature of air being drawn into the engine 102 may be measured using an intake air temperature (IAT) sensor 192. The engine system 100 may also include one or more other sensors 193, such as an ambient pressure sensor, an engine oil temperature sensor, one or more knock sensors, a compressor outlet pressure sensor and/or a throttle inlet pressure sensor. The ECM 114 may use signals from the sensors to make control decisions for the engine system 100.

The ECM 114 may communicate with a transmission control module 194 to coordinate shifting gears in a transmission (not shown). For example, the ECM 114 may reduce engine torque during a gear shift. The ECM 114 may communicate with a hybrid control module 196 to coordinate operation of the engine 102 and an electric motor 198. The electric motor 198 may also function as a generator, and may be used to produce electrical energy for use by vehicle electrical systems and/or for storage in a battery. In various implementations, various functions of the ECM 114, the transmission control module 194, and the hybrid control module 196 may be integrated into one or more modules.

Each system that varies an engine parameter may be referred to as an engine actuator. For example, the throttle actuator module 116 may adjust opening of the throttle valve 112 to achieve a target throttle opening area. The spark actuator module 126 controls the spark plugs to achieve a target spark timing relative to piston TDC. The fuel actuator module 124 controls the fuel injectors to achieve target fueling parameters. The phaser actuator module 158 may control the intake and exhaust cam phasers 148 and 150 to achieve target intake and exhaust cam phaser angles, respectively. The EGR actuator module 172 may control the EGR valve 170 to achieve a target EGR opening area. The boost actuator module 164 controls the wastegate 162 to achieve a target wastegate opening area. The cylinder actuator module 120 controls cylinder deactivation to achieve a target number of activated or deactivated cylinders.

The ECM 114 generates the target values for the engine actuators to cause the engine 102 to generate a target engine output torque. The ECM 114 generates the target values for the engine actuators using model predictive control, as discussed further below.

Referring now to FIG. 2, a functional block diagram of an example engine control system is presented. An example implementation of the ECM 114 includes a driver torque module 202, an axle torque arbitration module 204, and a propulsion torque arbitration module 206. The ECM 114 may include a hybrid optimization module 208. The ECM 114 also includes a speed control module 210, a speed trajectory module 212, a reserves/loads module 220, a torque requesting module 224, an air control module 228, a spark control module 232, a cylinder control module 236, and a fuel control module 240.

The driver torque module 202 may determine a driver torque request 254 based on a driver input 255 from the driver input module 104. The driver input 255 may be based on, for example, a position of an accelerator pedal and a position of a brake pedal. The driver input 255 may also be based on cruise control, which may be an adaptive cruise control system that varies vehicle speed to maintain a predetermined following distance. The driver torque module 202 may store one or more mappings of accelerator pedal position to target torque and may determine the driver torque request 254 based on a selected one of the mappings. The driver torque module 202 may also apply one or more filters to rate limit changes in the driver torque request 254.

An axle torque arbitration module 204 arbitrates between the driver torque request 254 and other axle torque requests 256. Axle torque (torque at the wheels) may be produced by various sources including an engine and/or an electric motor. For example, the axle torque requests 256 may include a torque reduction requested by a traction control system when positive wheel slip is detected. Positive wheel slip occurs when axle torque overcomes friction between the wheels and the road surface, and the wheels begin to slip against the road surface. The axle torque requests 256 may also include a torque increase request to counteract negative wheel slip, where a tire of the vehicle slips in the other direction with respect to the road surface because the axle torque is negative.

The axle torque requests 256 may also include brake management requests and vehicle over-speed torque requests. Brake management requests may reduce axle torque to ensure that the axle torque does not exceed the ability of the brakes to hold the vehicle when the vehicle is stopped. Vehicle over-speed torque requests may reduce the axle torque to prevent the vehicle from exceeding a predetermined speed. The axle torque requests 256 may also be generated by vehicle stability control systems.

The axle torque arbitration module 204 outputs a predicted torque request 257 and an immediate torque request 258 based on the results of arbitrating between the received torque requests 254 and 256. As described below, the predicted and immediate torque requests 257 and 258 from the axle torque arbitration module 204 may selectively be adjusted by other modules of the ECM 114 before being used to control the engine actuators.

In general terms, the immediate torque request 258 may be an amount of currently desired axle torque, while the predicted torque request 257 may be an amount of axle torque that may be needed on short notice. The ECM 114 controls the engine system 100 to produce an axle torque equal to the immediate torque request 258. However, different combinations of target values may result in the same axle torque. The ECM 114 may therefore adjust the target values to enable a faster transition to the predicted torque request 257, while still maintaining the axle torque at the immediate torque request 258.

In various implementations, the predicted torque request 257 may be set based on the driver torque request 254. The immediate torque request 258 may be set to less than the predicted torque request 257 under some circumstances, such as when the driver torque request 254 is causing wheel slip on an icy surface. In such a case, a traction control system (not shown) may request a reduction via the immediate torque request 258, and the ECM 114 reduces the engine torque output to the immediate torque request 258. However, the ECM 114 performs the reduction so the engine system 100 can quickly resume producing the predicted torque request 257 once the wheel slip stops.

In general terms, the difference between the immediate torque request 258 and the (generally higher) predicted torque request 257 can be referred to as a fast torque reserve. The fast torque reserve may represent the amount of additional torque (above the immediate torque request 258) that the engine system 100 can begin to produce with minimal delay, for example, by adjusting spark timing. Fast engine actuators are used to increase or decrease current axle torque with minimal delay. Fast engine actuators are defined in contrast with slow engine actuators.

In general terms, fast engine actuators can change the axle torque more quickly than slow engine actuators. Slow actuators may respond more slowly to changes in their respective target values than fast actuators do. For example, a slow actuator may include mechanical components that require time to move from one position to another in response to a change in target value. A slow actuator may also be characterized by the amount of time it takes for the axle torque to begin to change once the slow actuator begins to implement the changed target value. Generally, this amount of time will be longer for slow actuators than for fast actuators. In addition, even after beginning to change, the axle torque may take longer to fully respond to a change in a slow actuator.

For example only, the spark actuator module 126 may be a fast actuator. Spark-ignition engines may combust fuels including, for example, gasoline and ethanol, by applying a spark. By way of contrast, the throttle actuator module 116 may be a slow actuator.

For example, as described above, the spark actuator module 126 can vary the spark timing for a next firing event when the spark timing is changed between a last firing event and the next firing event. By way of contrast, changes in throttle opening take longer to affect engine output torque. The throttle actuator module 116 changes the throttle opening by adjusting the angle of the blade of the throttle valve 112. Therefore, when the target value for opening of the throttle valve 112 is changed, there is a mechanical delay as the throttle valve 112 moves from its previous position to a new position in response to the change. In addition, air flow changes based on the throttle opening are subject to air transport delays in the intake manifold 110. Further, increased air flow in the intake manifold 110 is not realized as an increase in engine output torque until the cylinder 118 receives additional air in the next intake stroke, compresses the additional air, and commences the combustion stroke.

Using these actuators as an example, a fast torque reserve can be created by setting the throttle opening to a value that would allow the engine 102 to produce the predicted torque request 257. Meanwhile, the spark timing can be set based on the immediate torque request 258, which is less than the predicted torque request 257. Although the throttle opening generates enough air flow for the engine 102 to produce the predicted torque request 257, the spark timing is retarded (which reduces torque) based on the immediate torque request 258. The engine output torque will therefore be equal to the immediate torque request 258.

When additional torque is needed, the spark timing can be set based on the predicted torque request 257 or a torque between the predicted and immediate torque requests 257 and 258. By the following firing event, the spark actuator module 126 may return the spark timing to an optimum value, which allows the engine 102 to produce the full engine output torque achievable with the air flow already present. The engine output torque may therefore be quickly increased to the predicted torque request 257 without experiencing delays from changing the throttle opening.

The axle torque arbitration module 204 may output the predicted torque request 257 and the immediate torque request 258 to a propulsion torque arbitration module 206. In various implementations, the axle torque arbitration module 204 may output the predicted and immediate torque requests 257 and 258 to the hybrid optimization module 208.

The hybrid optimization module 208 may determine how much torque should be produced by the engine 102 and how much torque should be produced by the electric motor 198. The hybrid optimization module 208 then outputs modified predicted and immediate torque requests 259 and 260, respectively, to the propulsion torque arbitration module 206. In various implementations, the hybrid optimization module 208 may be implemented in the hybrid control module 196.

The predicted and immediate torque requests received by the propulsion torque arbitration module 206 are converted from an axle torque domain (torque at the wheels) into a propulsion torque domain (torque at the crankshaft). This conversion may occur before, after, as part of, or in place of the hybrid optimization module 208.

The propulsion torque arbitration module 206 arbitrates between propulsion torque requests 290, including the converted predicted and immediate torque requests. The propulsion torque arbitration module 206 generates an arbitrated predicted torque request 261 and an arbitrated immediate torque request 262. The arbitrated torque requests 261 and 262 may be generated by selecting a winning request from among received torque requests. Alternatively or additionally, the arbitrated torque requests may be generated by modifying one of the received requests based on another one or more of the received torque requests.

For example, the propulsion torque requests 290 may include torque reductions for engine over-speed protection, torque increases for stall prevention, and torque reductions requested by the transmission control module 194 to accommodate gear shifts. The propulsion torque requests 290 may also result from clutch fuel cutoff, which reduces the engine output torque when the driver depresses the clutch pedal in a manual transmission vehicle to prevent a flare in engine speed.

The propulsion torque requests 290 may also include an engine shutoff request, which may be initiated when a critical fault is detected. For example only, critical faults may include detection of vehicle theft, a stuck starter motor, electronic throttle control problems, and unexpected torque increases. In various implementations, when an engine shutoff request is present, arbitration selects the engine shutoff request as the winning request. When the engine shutoff request is present, the propulsion torque arbitration module 206 may output zero as the arbitrated torque requests 261 and 262.

In various implementations, an engine shutoff request may simply shut down the engine 102 separately from the arbitration process. The propulsion torque arbitration module 206 may still receive the engine shutoff request so that, for example, appropriate data can be fed back to other torque requestors. For example, all other torque requestors may be informed that they have lost arbitration.

The speed control module 210 may also output predicted and immediate torque requests to the propulsion torque arbitration module 206. The torque requests from the speed control module 210 may prevail in arbitration when the ECM 114 is in a speed mode. Speed mode may be selected when the driver's foot is not depressing the accelerator pedal, such as when the vehicle is idling or coasting down from a higher speed. Alternatively or additionally, speed mode may be selected when the predicted torque request from the axle torque arbitration module 204 is less than a predetermined torque value.

The speed control module 210 receives a desired engine speed from the speed trajectory module 212, and controls the predicted and immediate torque requests to reduce the difference between the desired engine speed and the current engine speed. For example only, the speed trajectory module 212 may output a linearly decreasing desired engine speed for vehicle coastdown until an idle speed is reached. The speed trajectory module 212 may then continue outputting the idle speed as the desired engine speed.

The reserves/loads module 220 receives the arbitrated torque requests 261 and 262. The reserves/loads module 220 may adjust the arbitrated torque requests 261 and 262 to create a fast torque reserve and/or to compensate for one or more loads. The reserves/loads module 220 then outputs adjusted predicted and immediate torque requests 263 and 264 to the torque requesting module 224.

For example only, a catalyst light-off process or a cold start emissions reduction process may require retarded spark timing. The reserves/loads module 220 may therefore increase the adjusted predicted torque request 263 above the adjusted immediate torque request 264 to create retarded spark for the cold start emissions reduction process. In another example, the air/fuel ratio of the engine and/or the mass air flow may be directly varied, such as by diagnostic intrusive equivalence ratio testing and/or new engine purging. Before beginning these processes, a fast torque reserve may be created or increased to quickly offset decreases in engine output torque that result from leaning the air/fuel mixture during these processes.

The reserves/loads module 220 may also create or increase a fast torque reserve in anticipation of a future load, such as power steering pump operation or engagement of an air conditioning (NC) compressor clutch. The reserve for engagement of the NC compressor clutch may be created when the driver first requests air conditioning. The reserves/loads module 220 may increase the adjusted predicted torque request 263 while leaving the adjusted immediate torque request 264 unchanged to produce the torque reserve. Then, when the NC compressor clutch engages, the reserves/loads module 220 may increase the adjusted immediate torque request 264 by the estimated load of the NC compressor clutch.

The torque requesting module 224 receives the adjusted predicted and immediate torque requests 263 and 264. The torque requesting module 224 determines how the adjusted predicted and immediate torque requests 263 and 264 will be achieved. The torque requesting module 224 may be engine type specific. For example, the torque requesting module 224 may be implemented differently or use different control schemes for spark-ignition engines versus compression-ignition engines.

In various implementations, the torque requesting module 224 may define a boundary between modules that are common across all engine types and modules that are engine type specific. For example, engine types may include spark-ignition and compression-ignition. Modules prior to the torque requesting module 224, such as the propulsion torque arbitration module 206, may be common across engine types, while the torque requesting module 224 and subsequent modules may be engine type specific.

The torque requesting module 224 determines an air torque request 265 based on the adjusted predicted and immediate torque requests 263 and 264. The air torque request 265 may be a brake torque. Brake torque may refer to torque at the crankshaft under the current operating conditions.

Target values for airflow controlling engine actuators are determined based on the air torque request 265. More specifically, based on the air torque request 265, the air control module 228 determines a target wastegate opening area 266, a target throttle opening area 267, a target EGR opening area 268, a target intake cam phaser angle 269, and a target exhaust cam phaser angle 270. The air control module 228 determines the target wastegate opening area 266, the target throttle opening area 267, the target EGR opening area 268, the target intake cam phaser angle 269, and the target exhaust cam phaser angle 270 using model predictive control, as discussed further below.

The boost actuator module 164 controls the wastegate 162 to achieve the target wastegate opening area 266. For example, a first conversion module 272 may convert the target wastegate opening area 266 into a target duty cycle 274 to be applied to the wastegate 162, and the boost actuator module 164 may apply a signal to the wastegate 162 based on the target duty cycle 274. In various implementations, the first conversion module 272 may convert the target wastegate opening area 266 into a target wastegate position (not shown), and convert the target wastegate position into the target duty cycle 274.

The throttle actuator module 116 controls the throttle valve 112 to achieve the target throttle opening area 267. For example, a second conversion module 276 may convert the target throttle opening area 267 into a target duty cycle 278 to be applied to the throttle valve 112, and the throttle actuator module 116 may apply a signal to the throttle valve 112 based on the target duty cycle 278. In various implementations, the second conversion module 276 may convert the target throttle opening area 267 into a target throttle position (not shown), and convert the target throttle position into the target duty cycle 278.

The EGR actuator module 172 controls the EGR valve 170 to achieve the target EGR opening area 268. For example, a third conversion module 280 may convert the target EGR opening area 268 into a target duty cycle 282 to be applied to the EGR valve 170, and the EGR actuator module 172 may apply a signal to the EGR valve 170 based on the target duty cycle 282. In various implementations, the third conversion module 280 may convert the target EGR opening area 268 into a target EGR position (not shown), and convert the target EGR position into the target duty cycle 282.

The phaser actuator module 158 controls the intake cam phaser 148 to achieve the target intake cam phaser angle 269. The phaser actuator module 158 also controls the exhaust cam phaser 150 to achieve the target exhaust cam phaser angle 270. In various implementations, a fourth conversion module (not shown) may be included and may convert the target intake and exhaust cam phaser angles into target intake and exhaust duty cycles, respectively. The phaser actuator module 158 may apply the target intake and exhaust duty cycles to the intake and exhaust cam phasers 148 and 150, respectively. In various implementations, the air control module 228 may determine a target overlap factor and a target effective displacement, and the phaser actuator module 158 may control the intake and exhaust cam phasers 148 and 150 to achieve the target overlap factor and the target effective displacement.

The torque requesting module 224 may also generate a spark torque request 283, a cylinder shut-off torque request 284, and a fuel torque request 285 based on the adjusted predicted and immediate torque requests 263 and 264. The spark control module 232 may determine how much to retard the spark timing (which reduces engine output torque) from an optimum spark timing based on the spark torque request 283. For example only, a torque relationship may be inverted to solve for a target spark timing 286. For a given torque request (T_(Req)), the target spark timing (S_(T)) 286 may be determined based on: S _(T) =f ⁻¹(T _(Req),APC,I,E,AF,OT,#), where APC is an APC, I is an intake valve phasing value, E is an exhaust valve phasing value, AF is an air/fuel ratio, OT is an oil temperature, and # is a number of activated cylinders. This relationship may be embodied as an equation and/or as a lookup table. The air/fuel ratio (AF) may be the actual air/fuel ratio, as reported by the fuel control module 240.

When the spark timing is set to the optimum spark timing, the resulting torque may be as close to a minimum spark advance for best torque (MBT spark timing) as possible. Best torque refers to the maximum engine output torque that is generated for a given air flow as spark timing is advanced, while using fuel having an octane rating greater than a predetermined octane rating and using stoichiometric fueling. The spark timing at which this best occurs is referred to as an MBT spark timing. The optimum spark timing may differ slightly from MBT spark timing because of, for example, fuel quality (such as when lower octane fuel is used) and environmental factors, such as ambient humidity and temperature. The engine output torque at the optimum spark timing may therefore be less than MBT. For example only, a table of optimum spark timings corresponding to different engine operating conditions may be determined during a calibration phase of vehicle design, and the optimum value is determined from the table based on current engine operating conditions.

The cylinder shut-off torque request 284 may be used by the cylinder control module 236 to determine a target number of cylinders to deactivate 287. In various implementations, a target number of cylinders to activate may be used. The cylinder actuator module 120 selectively activates and deactivates the valves of cylinders based on the target number 287.

The cylinder control module 236 may also instruct the fuel control module 240 to stop providing fuel for deactivated cylinders and may instruct the spark control module 232 to stop providing spark for deactivated cylinders. The spark control module 232 may stop providing spark to a cylinder once an air/fuel mixture that is already present in the cylinder has been combusted.

The fuel control module 240 may vary the amount of fuel provided to each cylinder based on the fuel torque request 285. More specifically, the fuel control module 240 may generate target fueling parameters 288 based on the fuel torque request 285. The target fueling parameters 288 may include, for example, target mass of fuel, target injection starting timing, and target number of fuel injections.

During normal operation, the fuel control module 240 may operate in an air lead mode in which the fuel control module 240 attempts to maintain a stoichiometric air/fuel ratio by controlling fueling based on air flow. For example, the fuel control module 240 may determine a target fuel mass that will yield stoichiometric combustion when combined with a present mass of air per cylinder (APC).

FIG. 3 is a functional block diagram of an example implementation of the air control module 228. Referring now to FIGS. 2 and 3, as discussed above, the air torque request 265 may be a brake torque. A torque conversion module 302 converts the air torque request 265 from brake torque into base torque. The torque request resulting from the conversion of the air torque request 265 into base torque will be referred to as a base air torque request 304.

Base torques may refer to torque at the crankshaft made during operation of the engine 102 on a dynamometer while the engine 102 is warm and no torque loads are imposed on the engine 102 by accessories, such as an alternator and the NC compressor. The torque conversion module 302 may convert the air torque request 265 into the base air torque request 304, for example, using a mapping or a function that relates brake torques to base torques. In various implementations, the torque conversion module 302 may convert the air torque request 265 into another suitable type of torque, such as an indicated torque. An indicated torque may refer to a torque at the crankshaft attributable to work produced via combustion within the cylinders.

A target pressure ratio module 306 determines a first target pressure ratio 308 across the throttle valve 112. The air control module 228 may determine the target throttle opening area 267 based on the first target pressure ratio 308 and independent of the base air torque request 304 when the engine 102 is cranking. The target pressure ratio module 306 determines the first target pressure ratio 308 based on a first target MAP 310 and a throttle inlet air pressure (TIAP) 312. The target pressure ratio module 306 determines the first target pressure ratio 308 using a function or a mapping that relates the first target MAP 310 and the TIAP 312 to the first target pressure ratio 308. For example, the target pressure ratio module 306 may determine the first target pressure ratio 308 using the equation: TPR=Target MAP/TIAP, where TPR is the first target pressure ratio 308, Target MAP is the first target MAP 310, and TIAP is the TIAP 312. The TIAP 312 may be measured using the TIAP sensor 191. In implementations where the first target pressure ratio 308 is expressed as a percentage, the result of the above equation may be multiplied by 100.

A target MAP module 313 determines the first target MAP 310. The first target MAP 310 may be predetermined by, for example, measuring an actual MAP during an attempt to start the engine 102 and setting the first target MAP 310 equal to the actual MAP measured during a successful start of the engine 102. Additionally or alternatively, the target MAP module 313 may determine the first target MAP 310 based on barometric pressure and engine coolant temperature. In one example, the target MAP module 313 may adjust a predetermined value of the first target MAP 310 based on barometric pressure and engine coolant temperature to compensate for factors such as engine friction and pumping losses. Barometric pressure may be measured using one of the sensors 193. Engine coolant temperature may be measured using the ECT sensor 182.

An MPC module 314 generates the target values 266 and 268-270, and a second target pressure ratio 320 using MPC (Model Predictive Control). The MPC module 314 may be a single module or may comprise multiple modules. For example, the MPC module 314 may include a sequence determination module 316.

The sequence determination module 316 determines possible sequences of target values that could be used together during N future control loops. Each of the possible sequences identified by the sequence determination module 316 includes one sequence of N target values. More specifically, each possible sequence includes a sequence of N values for the target wastegate opening area 266, a sequence of N values for the second target pressure ratio 320 across the throttle valve 112, a sequence of N values for the target EGR opening area 268, a sequence of N values for the target intake cam phaser angle 269, and a sequence of N values for the target exhaust cam phaser angle 270. Each of the N values are for a corresponding one of the N future control loops. N is an integer greater than or equal to one. A pressure ratio across the throttle valve 112 refers to a ratio of a pressure at an output side of the throttle valve 112 to a pressure at an input side of the throttle valve 112. MAP may be used as the pressure at the output side of the throttle valve 112, TIAP may be used as the pressure at the input side of the throttle valve 112, and pressure ratios may be expressed as quotients (e.g., MAP/TIAP).

A prediction module 323 determines predicted responses of the engine 102 to the possible sequences of the target values, respectively, based on a mathematical model 324 of the engine 102, exogenous inputs 328, and feedback inputs 330. More specifically, based on a possible sequence of the target values, the exogenous inputs 328, and the feedback inputs 330, using the model 324, the prediction module 323 generates a sequence of N predicted torques of the engine 102 for the N control loops, a sequence of N predicted APCs for the N control loops, a sequence of N predicted amounts of external dilution for the N control loops, a sequence of N predicted amounts of residual dilution for the N control loops, a sequence of N predicted combustion phasing values for the N control loops, and a sequence of N predicted combustion quality values for the N control loops.

While an example of generating predicted torque, predicted APC, predicted external dilution, predicted residual dilution, predicted combustion phasing, and predicted combustion quality is described, the predicted parameters may include one or more other predicted engine operating parameters. For example, an efficiency parameter may be predicted in place of the predicted APC, and the efficiency parameter may be predicted torque divided by predicted APC.

The model 324 may include, for example, one or more functions or mappings calibrated based on characteristics of the engine 102. Dilution may refer to an amount of exhaust from a prior combustion event trapped within a cylinder for a combustion event. External dilution may refer to exhaust provided for a combustion event via the EGR valve 170. Residual dilution may refer to exhaust that remains in a cylinder and/or exhaust that is pushed back into the cylinder following the exhaust stroke of a combustion cycle. Residual dilution may also be referred to as internal dilution.

Combustion phasing may refer to a crankshaft position where a predetermined amount of fuel injected is combusted within a cylinder relative to a predetermined crankshaft position for combustion of the predetermined amount of injected fuel. For example, combustion phasing may be expressed in terms of CA50 relative to a predetermined CA50. CA50 may refer to a crankshaft angle (CA) where 50 percent of a mass of injected fuel has been combusted within a cylinder. The predetermined CA50 may correspond to a CA50 where a maximum amount of work is produced from the fuel injected and may be approximately 8.5—approximately 10 degrees after TDC (top dead center) in various implementations. While combustion phasing will be discussed in terms of CA50 values, another suitable parameter indicative of combustion phasing may be used. Additionally, while combustion quality will be discussed as coefficient of variation (COV) of indicated mean effective pressure (IMEP) values, another suitable parameter indicative of combustion quality may be used.

The exogenous inputs 328 may include parameters that are not directly affected by the throttle valve 112, the EGR valve 170, the turbocharger, the intake cam phaser 148, and the exhaust cam phaser 150. For example, the exogenous inputs 328 may include engine speed, IAT, and/or one or more other parameters. The feedback inputs 330 may include, for example, an estimated torque output of the engine 102, an exhaust pressure downstream of the turbine 160-1 of the turbocharger, the IAT, an APC of the engine 102, an estimated residual dilution, an estimated external dilution, and/or one or more other suitable parameters. The feedback inputs 330 may be measured using sensors (e.g., the IAT) and/or estimated based on one or more other parameters.

A cost module 332 determines a cost value for each of the possible sequences of the target values based on the predicted parameters determined for a possible sequence and output reference values 356. An example cost determination is discussed further below.

A selection module 344 selects one of the possible sequences of the target values based on the costs of the possible sequences, respectively. For example, the selection module 344 may select the one of the possible sequences having the lowest cost while satisfying target constraints 348 and prediction constraints 352. In various implementations, the model 324 may select the one of the possible sequences having the lowest cost while satisfying the target constraints 348 and the prediction constraints 352. In various implementations, satisfaction of the prediction constraints 352 may be considered in the cost determination. In other words, the cost module 332 may determine the cost values further based on the prediction constraints 352.

The selection module 344 may set the target values 266, 268-270, and 320 to the first ones of the N values of the selected possible sequence, respectively. In other words, the selection module 344 may set the target wastegate opening area 266 to the first one of the N values in the sequence of N values for the target wastegate opening area 266, set the second target pressure ratio 320 across the throttle valve 112 to the first one of the N values in the sequence of N values for the second target pressure ratio 320, set the target EGR opening area 268 to the first one of the N values in the sequence of N values for the target EGR opening area 268, set the target intake cam phaser angle 269 to the first one of the N values in the sequence of N values for the target intake cam phaser angle 269, and set the target exhaust cam phaser angle 270 to the first one of the N values in the sequence of N values for the target exhaust cam phaser angle 270.

During a next control loop, the MPC module 314 identifies possible sequences, generates the predicted parameters for the possible sequences, determines the cost of each of the possible sequences, selects of one of the possible sequences, and sets of the target values 266, 268-270, and 320 to the first ones of those values in the selected possible sequence, respectively. This process continues for each control loop.

A target constraint module 360 (see FIG. 2) sets the target constraints 348 for each of the target values 266, 268-270, and 320. In other words, the target constraint module 360 sets target constraints for the second target pressure ratio 320, target constraints for the target EGR opening area 268, target constraints for the target wastegate opening area 266, target constraints for the target intake cam phaser angle 269, and target constraints for the target exhaust cam phaser angle 270.

The target constraints 348 for each one of the target values 266, 268-270, and 320 may include a maximum value for an associated target value and a minimum value for that target value. The target constraint module 360 may generally set the target constraints 348 to predetermined operational ranges for the second target pressure ratio 320, the EGR valve 170, the wastegate 162, the intake cam phaser 148, and the exhaust cam phaser 150, respectively. However, the target constraint module 360 may vary one or more of the target constraints 348 under some circumstances.

For the second target pressure ratio 320, the maximum value may correspond to a maximum possible pressure ratio across the throttle valve 112. For example only, when the pressure ratio is expressed as a percentage (i.e., inlet pressure*100/outlet pressure), the maximum value may be approximately 99.7 or another suitable value. The minimum value for the second target pressure ratio 320 may be set based on a minimum pressure ratio across the throttle valve 112 to maintain proper combustion. The minimum value for the second target pressure ratio 320 may vary. The target constraint module 360 may determine the minimum value for the target pressure ratio, for example, based on one or more engine operating conditions using a function or a mapping.

A prediction constraint module 364 (see FIG. 2) sets the prediction constraints 352 for the predicted torque output of the engine 102, the predicted CA50, the predicted COV of IMEP, the predicted residual dilution, and the predicted external dilution. The prediction constraints 352 for each one of the predicted values may include a maximum value for an associated predicted parameter and a minimum value for that predicted parameter. For example, the prediction constraints 352 may include a minimum torque, a maximum torque, a minimum CA50 and a maximum CA50, a minimum COV of IMEP and a maximum COV of IMEP, a minimum residual dilution and a maximum residual dilution, and a minimum external dilution and a maximum external dilution.

The prediction constraint module 364 may generally set the prediction constraints 352 to predetermined ranges for the associated predicted parameters, respectively. However, the prediction constraint module 364 may vary one or more of the prediction constraints 352 under some circumstances.

A reference module 368 (see FIG. 2) generates the reference values 356 for the target values 266, 268-270, and 320, respectively. The reference values 356 include a reference value for each of the target values 266, 268-270, and 320. In other words, the reference values 356 include a reference wastegate opening area, a reference pressure ratio across the throttle valve 112, a reference EGR opening area, a reference intake cam phaser angle, and a reference exhaust cam phaser angle.

The reference module 368 may determine the reference values 356, for example, based on the air torque request 265 and/or the base air torque request 304. The reference values 356 provide references for setting the target values 266, 268-270, and 320, respectively. The reference values 356 may be used to determine the cost values for possible sequences, as discussed further below. The reference values 356 may also be used for one or more other reasons, such as by the sequence determination module 316 to determine possible sequences.

To determine the reference pressure ratio across the throttle valve 112, the reference module 368 may first determine a reference APC based on the air torque request 265 or the base air torque request 304, and then determine the reference pressure ratio across the throttle valve 112 based on the reference APC. The reference module 368 may determine the reference APC based on the air torque request 265 or the base air torque request 304 using the following relationship: APC=f ⁻¹(T _(A),RPM,S,I,E,AF,OT,#), where APC is the reference APC, ATR is the air torque request 265 or the base air torque request 304, I is an intake valve phasing value, E is an exhaust valve phasing value, AF is an air/fuel ratio, OT is an oil temperature, and # is a number of activated cylinders. This relationship may be embodied as an equation and/or as a lookup table. The air/fuel ratio (AF) may be the actual air/fuel ratio, as reported by the fuel control module 240. The reference module 368 may determine the reference pressure ratio across the throttle valve 112 based on the reference APC using a lookup table.

Instead of or in addition to generating sequences of possible target values and determining the cost of each of the sequences, the MPC module 314 may identify a sequence of possible target values having the lowest cost using convex optimization techniques. For example, the MPC module 314 may determine the target values 266, 268-270, and 320 using a quadratic programming (QP) solver, such as a Dantzig QP solver. In another example, the MPC module 314 may generate a surface of cost values for the possible sequences of the target values 266, 268-270, and 320 and, based on the slope of the cost surface, identify a sequence of possible target values having the lowest cost. The MPC module 314 may then test that sequence of possible target values to determine whether that sequence of possible target values satisfies the target constraints 348. If so, the MPC module 314 may set the target values 266, 268-270, and 320 to the first ones of the N values of that selected possible sequence, respectively, as discussed above.

If the target constraints 348 are not satisfied, the MPC module 314 selects another sequence of possible target values with a next lowest cost and tests that sequence of possible target values for satisfaction of the target constraints 348. The process of selecting a sequence and testing the sequence for satisfaction of the target constraints 348 may be referred to as an iteration. Multiple iterations may be performed during each control loop.

The MPC module 314 performs iterations until a sequence with the lowest cost that satisfies the target constraints 348 is identified. In this manner, the MPC module 314 selects the sequence of possible target values having the lowest cost while satisfying the target constraints 348 and the prediction constraints 352. If a sequence cannot be identified, the MPC module 314 may indicate that no solution is available.

The cost module 332 may determine the cost for the possible sequences of the target values 266, 268-270, and 320 based on relationships between: the predicted torque and torque requests; the possible target values and the respective target constraints 348; the predicted parameters and the respective prediction constraints 352; and the possible target values and the respective reference values 356. The relationships may be weighted, for example, to control the effect that each of the relationships has on the cost.

For example only, the cost module 332 may determine the cost for a possible sequence of the target values 266, 268-270, and 320 based on or using the following equation: Cost=Σ_(i=1) ^(N)ρ∈² +∥wT*(TP_(i)−BATR_(i))∥² subject to the target constraints 348 and the prediction constraints 352. Cost is the cost for the possible sequence of the target values 266, 268-270, and 320, TPi is the predicted torque of the engine 102 for an i-th one of the N control loops, BATRi is the base air torque request for the i-th one of the N control loops, and wT is a weighting value associated with the relationship between the predicted torque and the torque requests. BATR₁ is the base air torque request 304. In various implementations, BATR BATR₂-BATR_(N) may also be set to the base air torque request 304, or BATR₂-BATR_(N) may be set based on future engine torque requests for the future ones of the N control loops.

ρ is a weighting value associated with satisfaction of the prediction constraints 352. ϵ is a variable that the cost module 332 may set based on whether the prediction constraints 352 will be satisfied. For example, the cost module 332 may increase ϵ when a predicted parameter is greater than or less than the corresponding minimum or maximum value (e.g., by at least a predetermined amount). The cost module 332 may set ϵ to zero when all of the prediction constraints 352 are satisfied. ρ may be greater than the weighting value wT and other weighting values discussed below (wPR, wWG, wEGR, wIP, wEP) such that the cost determined for a possible sequence will be large if one or more of the prediction constraints 352 are not satisfied. This may help prevent selection of a possible sequence where one or more of the prediction constraints 352 are not satisfied.

The above equation can be expanded, for example, to: Cost=Σ_(i=1) ^(N)ρ∈² +∥wT*(TP_(i)−BATR_(i))∥² +∥wPR*(PTPRi−PRRef)∥² +∥wWG*(PTWGOi−EGORef)∥² +∥wEGR*(PTEGROi−EGRORef)∥² +∥wIP*(PTICPi−ICPRef)∥² +∥wEP*(PTECPi−ECPRef)∥², again subject to the target constraints 348 and the prediction constraints 352. PTPRi is a possible target pressure ratio across the throttle valve 112 for the i-th one of the N control loops, PRRef is the reference pressure ratio across the throttle valve 112, and wPR is a weighting value associated with the relationship between the possible target pressure ratio and the reference pressure ratio. PTWGOi is a possible target wastegate opening for the i-th one of the N control loops, WGORef is the reference wastegate opening, and wWG is a weighting value associated with the relationship between the possible target wastegate openings and the reference wastegate opening.

PTEGROi is a possible target EGR opening for the i-th one of the N control loops, EGRRef is the reference EGR opening, and wEGR is a weighting value associated with the relationship between the possible target EGR openings and the reference EGR opening. PTICi is a possible target intake cam phaser angle for the i-th one of the N control loops, ICPRef is the reference intake cam phaser angle, and wIP is a weighting value associated with the relationship between the possible target intake cam phaser angle and the reference intake cam phaser angle. PTECi is a possible target exhaust cam phaser angle for the i-th one of the N control loops, ECPRef is the reference exhaust cam phaser angle, and wEP is a weighting value associated with the relationship between the possible target exhaust cam phaser angle and the reference exhaust cam phaser angle.

The weighting value wT may be greater than the weighting values wPR, wWG, wEGR, wIP, and wEP. In this manner, the relationship between the predicted engine torque and the base air torque requests have a larger effect on the cost and, therefore, the selection of one of the possible sequences as discussed further below. The cost increases as the difference between the predicted engine torque and the base air torque request increases and vice versa.

The weighting values wPR, wWG, wEGR, wIP, and wEP may be less than all of the other weighting values. In this manner, during steady-state operation, the target values 266, 268-270, and 320 may settle near or at the reference values 356, respectively. During transient operation, however, the MPC module 314 may adjust the target values 266, 268-270, and 320 away from the reference values 356 in order to achieve the base air torque request 304, while satisfying the target constraints 348 and the prediction constraints 352.

A target area module 372 (FIG. 3) determines the target throttle opening area 267 based on the first target pressure ratio 308 across the throttle valve 112 and/or the second target pressure ratio 320 across the throttle valve 112. When the engine 102 is cranking, the target area module 372 may determine the target throttle opening area 267 based on the first target pressure ratio 308. In addition, the MPC module 314 may adjust the target values 266 and 268-270 to maintain the intake and exhaust cam phasers 148 and 150 in fixed positions, open the wastegate 162, and close the EGR valve 170.

For a first period (e.g., 0.5 seconds) after the engine 102 is started, the target area module 372 may determine the target throttle opening area 267 based on whichever one of the first target pressure ratio 308 and the second target pressure ratio 320 has a greater value. The second target pressure ratio 320 may be greater than the first target pressure ratio 308 when, for example, the driver tips into the accelerator pedal. Thus, during the first period after the engine 102 starts, the target area module 372 may determine the target throttle opening area 267 based the first target pressure ratio 308 unless the driver tips into the accelerator pedal. If the driver tips into the accelerator pedal during the first period after the engine 102 starts, the target area module 372 may determine the target throttle opening area 267 based the second target pressure ratio 320.

The target area module 372 may determine when the engine 102 is started based on engine speed. For example, the target area module 372 may determine that the engine 102 is started when the engine speed is greater than a predetermined speed. The predetermined speed may be within a range from 400 RPM (revolutions per minute) to 600 RPM. The target area module 372 may determine the engine speed based on the crankshaft position from the CKP sensor 180.

When the engine 102 starts, the speed of the engine 102 may rise (increase) abruptly before settling (decreasing) to an idle speed. This abrupt rise and fall in engine speed may be referred to as engine flare. The target area module 372 may adjust the length of the first period to ensure that the engine speed reaches its maximum value during an engine flare before the first period ends. To accomplish this, the target area module 372 may determine the duration of the first period based on engine oil temperature and/or barometric pressure. To this end, mechanical friction in the engine 102 may be inversely proportional to the engine oil temperature, and the torque output the engine 102 may be directly proportional to the barometric pressure. Thus, the amount of time that the engine speed takes to reach its maximum value during engine startup may increase as the engine oil temperature decreases and/or the barometric pressure decreases. Therefore, the target area module 372 may increase the duration of the first period as the engine oil temperature decreases and/or the barometric pressure decreases. Conversely, the amount of time that the engine speed takes to reach its maximum value during engine startup may decrease as the engine oil temperature increases and/or the barometric pressure increases. Therefore, the target area module 372 may decrease the duration of the first period as the engine oil temperature increases and/or the barometric pressure increases. The engine oil temperature may be measured using one of the sensors 193. The barometric pressure may be measured using the MAP sensor 184 and/or the TIAP sensor 191 before the engine 102 starts cranking.

When the first period ends, the target area module 372 may stop determining the target throttle opening area 267 based on the first target pressure ratio 308 and start determining the target throttle opening area 267 based on the second target pressure ratio 320. As discussed above, the first target pressure ratio 308 is determined independent of the base air torque request 304, and the second target pressure ratio 320 is determined based on the base air torque request 304. Thus, when the first period ends, the target area module 372 may start determining the target throttle opening area 267 based on the base air torque request 304 for the first time.

If the first target pressure ratio 308 and the second target pressure ratio 320 are significantly different when the first period ends, the transition in the way in which the target throttle opening area 267 is determined may yield noticeable engine flare or jerk. To prevent this, when the first period ends, a torque initialization module 374 may initialize the base air torque request 304 based on a reference torque 376 to yield an initialized base air torque request 378. Although shown separately in FIG. 3, the reference torque 376 may be one of the reference values 356 sent from the reference module 368 (FIG. 2) to the air control module 228. The reference module 368 may determine the reference torque 376 based on the first target pressure ratio 308 using (an inverse of) the relationships used to determine the reference pressure ratio across the throttle valve 112 based on the air torque request 265 and the base air torque request 308. The torque initialization module 374 may initialize the base air torque request 304 by setting the base air torque request 304 equal to the reference torque 376. The torque initialization module 374 may then adjust the initialized base air torque request 378 at a predetermined rate to gradually decrease a difference between the (uninitialized value of) the base air torque request 304 and the initialized base air torque request 378.

In various implementations, the torque initialization module 376 may reside in the speed control module 210 (FIG. 2) instead of the air control module 228. Additionally or alternatively, the torque initialization module 376 may initialize the predicted and immediate torques that are output by the speed control module 210 instead of initializing the base air torque request 304. The torque initialization module 376 may then adjust the initialized predicted and immediate torque requests at a predetermined rate to gradually decrease a difference between uninitialized values of the predicted and immediate torque requests and the initialized predicted and immediate torque requests. The uninitialized values of the predicted and immediate torque requests may be the values of the predicted and immediate torque requests that are determined based on the desired engine speed and the current engine speed. The torque initialization module 376 may initialize the predicted torque request that is output by the speed control module 210 in the same way that the torque initialization module 376 initializes the base air torque request 304. The torque initialization module 376 may initialize the immediate torque request that is output by the speed control module 210 by setting the immediate torque request equal to a current torque output. The torque initialization module 376 may determine the current torque output based on a commanded spark timing and a current APC using an inverse of the relationship used to determine the target spark timing 286 based on the spark torque request 283.

Referring now to FIG. 4, an example implementation of the target area module 372 includes a target MAP module 404. The target MAP module 404 selects one of the first target pressure ratio 308 across the throttle valve 112 and the second target pressure ratio 320 across the throttle valve 112, and determines a target MAP 408 based on the selected target pressure ratio. The target MAP module 404 determines the target MAP 408 using a function or a mapping that relates the selected target pressure ratio and the TIAP 312 to the target MAP 408. For example, the target MAP module 404 may determine the target MAP 408 based on or using the equation: Target MAP=TPR*TIAP, where Target MAP is the target MAP 408, TPR is the selected target pressure ratio across the throttle valve 112, and TIAP is the TIAP 312. In implementations where the selected target pressure ratio is expressed as a percentage, the result of the above equation may be divided by 100.

The target MAP module 404 may select the first target pressure ratio 308 when the engine 102 is cranking. The target MAP module 404 may determine that the engine 102 is cranking when the engine speed is greater than zero and less than or equal to the predetermined speed. For the first period after the engine 102 is started, the target MAP module 404 may select the one of the first target pressure ratio 308 and the second target pressure ratio 320 that has a greater value.

A target APC module 416 determines a target mass of air per cylinder (APC) 420 based on the target MAP 408, the target intake cam phaser angle 269, and the target exhaust cam phaser angle 270. For example, the target APC module 416 determines the target APC 420 using one of a function and a mapping that relates target MAPs, target intake cam phaser angles, and target exhaust cam phaser angles to target APCs.

A target MAF module 424 determines a target mass air flowrate (MAF) 428 into the engine 102 based on the target APC 420, an engine speed 432, and a number of activated cylinders 436 of the engine 102. The number of activated cylinders 436 corresponds to the number of the cylinders of the engine 102 that are activated. The engine speed 432 may be determined based on crankshaft position measured using the CKP sensor 180. The target MAF module 424 determines the target MAF 428 using one of a function and a mapping that relates target APCs, engine speeds, and numbers of activated cylinders to target MAFs. For example, the target MAF module 424 may determine the target MAF 428 based on or using the equation:

${{{Target}\mspace{14mu}{MAF}} = \frac{{TAPC}*{Cyls}*{RPM}}{120000}},$ where Target MAF is the target MAF 428, TAPC is the target APC 420, Cyls is the number of activated cylinders 436, and RPM is the engine speed 432 in revolutions per minute. The value 120000 is an example value and may be different for different engines. Firing period, or the period between firing events of the cylinders, may be 120000/(cyls*RPM). The target MAF 428 (e.g., in g/s) may be determined based on the target APC 420 divided by the firing period, which provides the equation above.

A target area module 440 determines the target throttle opening area 267 for the throttle valve 112 based on the target MAF 428. The target area module 440 determines the target throttle opening area 267 further based on the second target pressure ratio 320 across the throttle valve 112, and the TIAP 312. The target area module 440 determines the target throttle opening area 267 using one of a function and a mapping that relates target MAFs, target pressure ratios, and TIAPs to target throttle openings. For example, the target area module 440 may determine the target throttle opening area 267 using the equation:

${TTO} = \frac{{TMAF}*\sqrt{R*{TIAT}}}{{TIAP}*{\Phi({TPR})}}$ where TTO is the target throttle opening area 267, TIAT is a throttle inlet air temperature (TIAT), TMAF is the target MAF 428, R is the ideal gas constant, TIAP is the TIAP 312, TPR is the second target pressure ratio 320, and ϕ represents an air density function. The TIAT may be measured using a sensor or determined based on one or more other parameters, for example, using a function or a mapping.

As stated above, the throttle actuator module 116 controls the throttle valve 112 based on the target throttle opening area 267. By determining the second target pressure ratio 320 based on the base air torque request 304 and determining the target throttle opening area 267 based on the second target pressure ratio 320, the MPC module 314 may provide better torque response characteristics (e.g., faster and with less over and/or undershoot) than implementations where the MPC module 314 determines the target throttle opening area 267 directly based on the base air torque request 304.

Referring now to FIG. 5, an example method of controlling the throttle valve 112, the intake cam phaser 148, the exhaust cam phaser 150, the wastegate 162 (and therefore the turbocharger), and the EGR valve 170 using MPC (model predictive control) begins at 502. At 504, the torque requesting module 224 determines the air torque request 265 based on the adjusted predicted and immediate torque requests 263 and 264. At 508, the torque conversion module 302 may convert the air torque request 265 into the base air torque request 304 or into another suitable type of torque for use by the MPC module 314.

The sequence determination module 316 determines possible sequences of the target values 266, 268-270, and 320 at 512. At 516, the prediction module 323 determines the predicted parameters for each of the possible sequences of target values. The prediction module 323 determines the predicted parameters for the possible sequences based on the model 324 of the engine 102, the exogenous inputs 328, and the feedback inputs 330. More specifically, based on a possible sequence of the target values, the exogenous inputs 328, and the feedback inputs 330, using the model 324, the prediction module 323 may generate a sequence of N predicted torques of the engine 102 for the N control loops, a sequence of N predicted APCs for the N control loops, a sequence of N predicted amounts of external dilution for the N control loops, a sequence of N predicted amounts of residual dilution for the N control loops, a sequence of N predicted combustion phasing values for the N control loops, and a sequence of N predicted combustion quality values for the N control loops.

The cost module 332 determines the costs for the possible sequences, respectively, at 520. For example only, the cost module 332 may determine the cost for a possible sequence of the target values 266, 268-270, and 320 using the equation: Cost=Σ_(i=1)ρ∈² +∥wT*(TP_(i)−BATR_(i))∥², or the equation: Cost=Σ_(i=1) ^(N)ρ∈² ∥wT*(TP_(i)−BATR_(i))∥² +∥wPR*(PTPRi−PRRef)∥² +∥wWG*(PTWGOi−EGORef)∥² +∥wEGR*(PTEGROi−EGRORef)∥² +∥wIP*(PTICPi−ICPRef)∥² +∥wEP*(PTECPi−ECPRef)∥², subject to the target constraints 348 and the prediction constraints 352, as discussed above.

The selection module 344 selects one of the possible sequences of the target values 266, 268-270, and 320 based on the costs of the possible sequences, respectively, at 524. For example, the selection module 344 may select the one of the possible sequences having the lowest cost. Instead of or in addition to determining possible sequences of the target values at 524 and determining the cost of each of the sequences, the MPC module 314 may identify a sequence of possible target values having the lowest cost using convex optimization techniques, as discussed above.

The MPC module 314 may determine whether the selected one of the possible sequences satisfies the target constraints 348 at 528. If 528 is true, control may continue with 536. If 528 is false, the MPC module 314 may select another one of the possible sequences with the next lowest cost at 532, and control may return to 528. In this manner, the sequence with the lowest cost that satisfies the target constraints 348 will be used.

At 536, the target MAP module 404 determines the target MAP 408 based on the second target pressure ratio 320 across the throttle valve 112 and the TIAP 312. The target APC module 416 determines the target APC 420 based on the target MAP 408, the target intake cam phaser angle 269, and the target exhaust cam phaser angle 270 at 540.

The target MAF module 424 determines the target MAF 428 at 544 based on the target APC 420, the engine speed 432, and the number of activated cylinders 436. At 548, the target area module 440 determines the target throttle opening area 267 based on the target MAF 428, the second target pressure ratio 320, and the TIAP 312.

At 552, the first conversion module 272 converts the target wastegate opening area 266 into the target duty cycle 274 to be applied to the wastegate 162, the second conversion module 276 converts the target throttle opening area 267 into the target duty cycle 278 to be applied to the throttle valve 112. The third conversion module 280 also converts the target EGR opening area 268 into the target duty cycle 282 to be applied to the EGR valve 170 at 540. The fourth conversion module may also convert the target intake and exhaust cam phaser angles 269 and 270 into the target intake and exhaust duty cycles to be applied to the intake and exhaust cam phasers 148 and 150, respectively.

At 556, the throttle actuator module 116 controls the throttle valve 112 to achieve the target throttle opening area 267, and the phaser actuator module 158 controls the intake and exhaust cam phasers 148 and 150 to achieve the target intake and exhaust cam phaser angles 269 and 270, respectively. For example, the throttle actuator module 116 may apply a signal to the throttle valve 112 at the target duty cycle 278 to achieve the target throttle opening area 267.

Also at 556, the EGR actuator module 172 controls the EGR valve 170 to achieve the target EGR opening area 268, and the boost actuator module 164 controls the wastegate 162 to achieve the target wastegate opening area 266. For example, the EGR actuator module 172 may apply a signal to the EGR valve 170 at the target duty cycle 282 to achieve the target EGR opening area 268, and the boost actuator module 164 may apply a signal to the wastegate 162 at the target duty cycle 274 to achieve the target wastegate opening area 266. While the method FIG. 5 is shown as ending at 560, FIG. 5 may be illustrative of one control loop, and control loops may be executed at a predetermined rate.

Referring now to FIG. 6, an example method of controlling actuators of the engine 102 to adjust intake airflow during an engine start starts at 602. At 604, the target area module 372 determines whether the engine 102 is cranking. The target area module 372 may determine that the engine 102 is cranking when a starter of the engine 102 is engaged and the engine speed is greater than zero and less than or equal to a predetermined speed (e.g., a speed between 400 RPM and 500 RPM). If the engine 102 is cranking, the method continues at 606. Otherwise, the target area module 372 continues to determine whether the engine 102 is cranking.

At 606, the target pressure ratio module 306 determines the first target pressure ratio 308 across the throttle valve 112 based on the first target MAP 310 and the TIAP 312 as discussed above with reference to FIG. 3. At 608, the throttle actuator module 116 actuates the throttle valve 112 based on the first target pressure ratio 308. For example, the target area module 372 may determine the target throttle opening area 267 based on the first target pressure ratio 308, and the throttle actuator module 116 may actuate the throttle valve 112 based on the target throttle opening area 267.

At 610, the target area module 372 determines whether the engine 102 is started. The target area module 372 may determine that the engine 102 is started when the engine speed is greater than the predetermined speed. If the engine 102 is started, the method continues at 612. Otherwise, the method continues at 606.

At 612, the MPC module 314 determines the second target pressure ratio 320 across the throttle valve 112 using MPC (Model Predictive Control). For example, the MPC module 314 may identify sets of possible values of the second target pressure ratio 320 and the target values 266 and 268-270 based on the base air torque request 304. The MPC module 314 may then predict operating parameters of the engine 102, such as the torque output of the engine 102, in response to each set of possible target values, and determine cost values for the predicted operating parameters. The MPC module 314 may then select the set of possible target values that has the lowest cost while satisfying the target constraints 348 and the prediction constraints 352, and set the second target pressure ratio 320 equal to the possible value of the second target pressure ratio 320 in the selected set.

At 614, the target area module 372 determines the duration of a first period based on engine oil temperature and/or barometric pressure. For example, the target area module 372 may increase the duration of the first period as the barometric pressure decreases and vice versa. The barometric pressure may be measured using the MAP sensor 184 and/or the TIAP sensor 191 before the engine 102 starts cranking.

At 616, the target area module 372 determines whether the period since the engine 102 started is less than the first period. If the period since the engine 102 started is less than the first period, the method continues at 618. Otherwise, the method continues at 620.

At 618, the throttle actuator module 116 actuates the throttle valve 112 based on a maximum value of the first and second target pressure ratios 308 and 320. For example, the target area module 372 may determine the target throttle opening area 267 based on the maximum value of the first and second target pressure ratios 308 and 320, and the throttle actuator module 116 may actuate the throttle valve 112 based on the target throttle opening area 267.

At 620, the reference module 368 determines the reference torque 376 based on the first target pressure ratio 308. At 622, the torque initialization module 374 initializes the base air torque request 304 based on the reference torque 376. For example, the torque initialization module 374 may initialize the base air torque request 304 by setting the base air torque request 304 equal to the reference torque 376. The torque initialization module 374 may then adjust the initialized base air torque request at a predetermined rate to gradually decrease a difference between the initialized base air torque request and an uninitialized value of the base air torque request 304. The method ends at 624.

The methods of FIGS. 5 and 6 may be implemented independently or in conjunction with one another. In an example of the latter, the method of FIG. 6 may be used to determine the target throttle opening area 267 at 548 of FIG. 5. The methods of FIGS. 5 and 6 are described in the context of the modules of FIGS. 2 through 4. However, the particular modules that perform the steps of the methods may be different than the modules mentioned above and/or the methods may be implemented apart from the modules of FIGS. 2 through 4.

Referring now to FIG. 7, an engine control mode signal 702, an engine speed signal 704, a fuel enabling signal 706, an actual MAP signal 708, and a target MAP signal 710 are plotted with respect to an x-axis 712 and a y-axis 714. The x-axis represents time. The y-axis represents the magnitudes of the signals 702-710.

The engine control mode signal 702 is adjusted to switch the air control module 228 between a crank mode and a run mode. In the crank mode, the air control module 228 controls the airflow actuators of the engine 102 based on the first target MAP 310 and independent of the base air torque request 304. In the run mode, the air control module 228 controls the airflow actuators of the engine 102 based on the base air torque request 304 and independent of the first target MAP 310.

The fuel enabling signal 706 is adjusted to switch the fuel control module 240 between a disabled mode and an enabled mode. In the disabled mode, the fuel control module 240 does not provide fuel to cylinders of the engine 102. In the enabled mode, the fuel control module 240 provides fuel to cylinders of the engine 102.

The engine speed signal 704 represents the engine speed determined based on the crankshaft position measured using the CKP sensor 180. The actual MAP signal 708 represents the manifold pressure measured using the MAP sensor 184. The target MAP signal 710 represents the first target MAP 310 generated by the target MAP module 313.

In the period before 716, the engine 102 is stopped. Thus, the engine speed signal 704 is at 0 RPM, and the actual MAP signal 708 is at barometric pressure. In addition, the engine control mode signal 702 is adjusted to a value corresponding to the crank mode, and the target MAP signal 710 is adjust to approximately 40 kilopascals.

At 716, the engine 102 starts cranking. Thus, between 716 and 718, the engine speed signal 704 increases to approximately 150 RPM. In addition, at 718, the fuel enabling signal 706 is adjusted to a value corresponding to the enabled mode.

At 720, fuel provided to cylinders of the engine 102 starts to combust. Thus, the engine speed signal 704 increases rapidly, and the actual MAP signal 708 starts to decrease. At 722, the engine speed signal 704 is between 400 RPM and 500 RPM, and the target area module 372 determines that the engine 102 is started.

At 724, the engine speed signal 704 reaches a peak value of 1600 RPM and starts to decrease. The period between 722 and 726 corresponds to the first period discussed above with reference to FIGS. 3, 4, and 6. Thus, at 726, the first period ends, the engine control mode signal 702 is adjusted to a value corresponding to the run mode, and the target MAP module 313 stops generating the target MAP signal 710. As indicated above, the target area module 372 may determine the first period based on engine oil temperature and actual MAP such that the first period does not end until after the engine speed signal 704 reaches its peak value and starts to decrease. At 728, the actual MAP signal 708 stops decreasing and remains at a steady-state value. At 730, the engine speed signal 704 reaches an idle speed of 800 RPM.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

In this application, including the definitions below, the term “module” or the term “controller” may be replaced with the term “circuit.” The term “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules that are connected via interface circuits. For example, multiple modules may allow load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish some functionality on behalf of a client module.

The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple modules. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple modules. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more modules.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language) or XML (extensible markup language), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective C, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5, Ada, ASP (active server pages), PHP, Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, and Python®.

None of the elements recited in the claims are intended to be a means-plus-function element within the meaning of 35 U.S.C. § 112(f) unless an element is expressly recited using the phrase “means for,” or in the case of a method claim using the phrases “operation for” or “step for.” 

What is claimed is:
 1. A system comprising: a target pressure ratio module that determines a first target pressure ratio across a throttle valve of an engine based on a first target pressure within an intake manifold of the engine and a throttle inlet air pressure; a torque requesting module that generates a torque request for the engine based on at least one of a driver input and a target engine speed; model predictive control (MPC) module that determines a second target pressure ratio based on the torque request; a target area module that: determines a target opening area of the throttle valve based on the first target pressure ratio, and independent of engine torque demand, when the engine is starting; and during a first period after the engine is started, determines the target opening area based on whichever one of the first target pressure ratio and the second target pressure ratio has a greater value; and a throttle actuator module that actuates the throttle valve based on the target opening area.
 2. The system of claim 1 wherein the first target pressure is predetermined.
 3. The system of claim 1 wherein the target area module determines the duration of the first period based on an engine oil temperature and a pressure measured within the intake manifold of the engine.
 4. The system of claim 1 wherein the MPC module further: identifies sets of possible target values based on the torque request, each of the sets of possible target values including a target pressure ratio across the throttle valve; predicts operating parameters of the engine for the sets of possible target values; determines cost values for the predicted operating parameters; selects one of the sets of possible target values based on the cost values; and sets target values to the possible target values of the selected set, the set target values including the second target pressure ratio across the throttle valve.
 5. The system of claim 1 further comprising: a reference module that determines a reference torque based on the first target pressure ratio; and a torque initialization module that initializes the torque request when the first period ends by setting the torque request equal to the reference torque.
 6. The system of claim 5 wherein, after the first period ends, the torque initialization module adjusts the torque request at a predetermined rate to decrease a difference between the initialized torque request and an uninitialized value of the torque request.
 7. A method comprising: determining a first target pressure ratio across a throttle valve of an engine based on a first target pressure within an intake manifold of the engine and a throttle inlet air pressure; generating a torque request for the engine based on at least one of a driver input and a target engine speed; determining a second target pressure ratio based on the torque request; determining a target opening area of the throttle valve based on the first target pressure ratio, and independent of engine torque demand, when the engine is starting; during a first period after the engine is started, determining the target opening area based on whichever one of the first target pressure ratio and the second target pressure ratio has a greater value; and actuating the throttle valve based on the target opening area.
 8. The method of claim 7 wherein the first target pressure is predetermined.
 9. The method of claim 7 further comprising determining duration of the first period based on an engine oil temperature and a pressure measured within the intake manifold of the engine.
 10. The method of claim 7 further comprising: identifying sets of possible target values based on the torque request, each of the sets of possible target values including a target pressure ratio across the throttle valve; predicting operating parameters of the engine for the sets of possible target values; determining cost values for the predicted operating parameters; selecting one of the sets of possible target values based on the cost values; and setting target values to the possible target values of the selected set, the set target values including the second target pressure ratio across the throttle valve.
 11. The method of claim 7 further comprising: determining a reference torque based on the first target pressure ratio; and initializing the torque request when the first period ends by setting the torque request equal to the reference torque.
 12. The method of claim 11 further comprising, after the first period ends, adjusting the torque request at a predetermined rate to decrease a difference between the initialized torque request and an uninitialized value of the torque request.
 13. The system of claim 1 further comprising a target manifold absolute pressure (MAP) module that determines the first target pressure based on barometric pressure and an engine coolant temperature.
 14. The method of claim 7 further comprising determining the first target pressure based on barometric pressure and an engine coolant temperature.
 15. A system comprising: a target pressure ratio module that determines a first target pressure ratio across a throttle valve of an engine based on a first target pressure within an intake manifold of the engine and a throttle inlet air pressure; a torque requesting module that generates a torque request for the engine based on at least one of a driver input and a target engine speed; a model predictive control (MPC) module that determines a second target pressure ratio based on the torque request; a target area module that: determines a target opening area of the throttle valve based on the first target pressure ratio, and independent of the torque request, when the engine is starting; and during a first period after the engine is started, determines the target opening area based on whichever one of the first target pressure ratio and the second target pressure ratio has a greater value; and a throttle actuator module that actuates the throttle valve based on the target opening area.
 16. The system of claim 15 further comprising a target manifold absolute pressure (MAP) module that determines the first target pressure based on barometric pressure and an engine coolant temperature.
 17. The system of claim 15 further comprising: a reference module that determines a reference torque based on the first target pressure ratio; and a torque initialization module that initializes the torque request when the first period ends by setting the torque request equal to the reference torque.
 18. The system of claim 17 wherein, after the first period ends, the torque initialization module adjusts the torque request at a predetermined rate to decrease a difference between the initialized torque request and an uninitialized value of the torque request. 